The present invention relates in general to a milking claw incorporating a novel valve design suitable for use in a milking machine as well as to a milking system incorporating suitably a plurality of such valves.
In known suction actuated milking systems, use has been made of a claw, providing a confluence for the milk flowing in from all the teatcups of the cluster, two teatcups in the case of equipment for milking goats or sheep and four teatcups for milking cows. The milk flows from the claw to a milk-receiving vessel. It has been found advantageous to provide a means to shut off the flow of air through the valve when the teatcups are removed from or fall off the teats, or prior to removal of the teatcups from the teats. This can be accomplished both manually and automatically. Known claw valves generally used for this purpose utilize a central shaft provided with a knob outside the valve body for manual operation, and a conical element sealing against a valve seat in its closed position. One such valve is shown and described in GB-B 881 282. This valve, with its through-shaft extending from the flow chamber to the outside air, has been prone to leakage, allowing impurities to be drawn into the system. The pulling and pushing of the knob necessary to open or close the valve requires the use of two hands and can have ergonomic disadvantages when repeated many times.
After removal of the teatcup, this known valve is designed to automatically shut off when air flows, at an elevated flow rate, through the valve from the teatcup, as a result of the dynamic force of the rapidly moving air on the bottom of the valve element, and reduced counterpressure on the other side of the element. Unfortunately, the valve may also unintentionally close if there is a very high rate of milk flow, which is clearly disadvantageous.
The object of the present invention is thus to provide a milking claw and a milking system incorporating such claws, which do not have these disadvantages, in a simple, reliable and easily operated design having a completely sealed of chamber with no penetrating elements.
The present invention fulfills these and other objects by providing a milking claw valve for shutting off and turning on vacuum-induced flow from a teatcup or teatcups in a milking machine, said valve including: a valve body having at least one inlet for milk flow from a teatcup and an outlet for milk flow from said valve, as well as a valve seat, a diaphragm mounted in said valve body said diaphragm being movable between an open position permitting flow from said inlet(s) to said outlet, and a closed position sealing against said valve seat, cutting off flow between said inlet(s) and said outlet, a manual actuator mounted in or on said valve body to swing or rotate between at least first and second positions, a non-extendible link connected between said manual actuator and a point on said diaphragm; the diaphragm being held in its open position by means of said link when said manual actuator is in its first position; the diaphragm being released to allow it to assume its closed position, when said manual actuator is moved to its second position; said diaphragm, when in its open position, exerting via the link a force on the manual actuator, urging it towards its first position.
According to a preferred embodiment of the present invention the manual actuator, which, for example, can be a lever or rotatable knob is biased towards its second position; said diaphragm, when in its open position, exerting via the link an opposing force on the manual actuator, urging it towards its first position; said opposing force, when there is a predetermined suction which induces liquid flow through the valve body, overcoming the biasing force urging the actuator towards its second position; said opposing force not overcoming the biasing force when there is a drop below said predetermined suction for the liquid flow through the valve.
This provides for automatic closing without the disadvantages of inadvertent closing.
The present invention also encompasses a claw comprising a valve according to the invention, and a milking system comprising: a vacuum source, a milk receiving container, at least one cluster having a claw according to the invention and at least two teatcups.